Spark plug



G. MAROTTA.

SPARK PLUG."

APPLICATION FILED SEPT. 2. 1920.

Patented May 9, 1922;

UNITED STATES PATENT OFFICE.

GABRIEL HAROTTA, OF SEATTLE, WASHINGTON, A SSIGNOR 0F ONE-HALE TO ABRAM VAN AALST, OF SEATTLE, WASHINGTON.

SPARK PLUG.

Application filed' September 2, 1920. Serial No. 407,781.

To all whom it may concern:

Be it known that I, GABRIEL MAROTTA, a

and the object of my improvements is to provide a spark plug having a plurality of terminals on the end thereof that are arranged in such a manner as to make it necessary for a spark to leap a plurality of gaps before reaching the grounded side of the circuit thereby affording a multiple spark for the purpose'of insuring ignition and eliminating liability of short circuiting of the plug by carbonizing.

Another object is to provide a plug of this I character which is of strong and simple construction, inexpensive to manufacture, eflicient in operation and obviating either a leakage of gas or a leakage of electrical current.

With the above and other objects in view as will appear from the following description, the invention consists in the novel construction, adaptation and combination of parts as will be hereinafter described and claimed.

In the accompanying drawings, Figure l is a view in'vertical mid-section of a spark plug constructed in accordance with this invention, and Fig. 2 is a plan view of the bottom end of the plug.

Like reference numerals designate like parts throughout the several views.

Referring to the drawings, the numeral 5 designates a tubular metal shell or body which adjacent to its lower end is threaded as at 6 to adapt it to be screwed into an opening therefor in an engine cylinder and above such threaded provided with a able portion 7.

Extending axially through the shell 5 is a sleeve 8 of porcelain, or an equivalent insulating material having a head 9 at its lower end provided with a convex extremity l1 and affording an annular shoulder 10 above the head.

The sleeve 8 is of less diameter than the polygonal wrench engage-= opening 12 therefor in the shell 5 to provide an annular air space about the sleeve.

Specification of Letters Patent.

portion said body is desirably Patented May 9, 1922.

the upper end of the shell and the sleeve 8 to thereby securely hold the relation with the shell.

The head 9 is surrounded by a packing 16 of insulating material as asbestos and which,

latter in spaced in turn, is enclosed within a copper jacket 17. The copper jacket 17 fits snugly within the enlarged bore at the lower end of the shell 5 and against an annular shoulder 18.

The lower portion of the shell 5 preferably tapers as at 20 and the extreme bottom edge of such shell is bent or crimped under the end of the head 9 as at 21 to thereby retain the sleeve within the shell 5.

The sleeve and cap 13 are centrally bored for the reception of an electrode 22 having a relatively small head 23 at its lower end and having its top end threaded for the reception of nuts 24. and 25 between which an electric circuit wire 26 may be secured. A

washer 27 may be interposed between the nut 25 and cap 13.

Secured in the lowerend of the sleeve head 9 and protruding below the same is a plurality of metal posts 28.

7 These posts serve as insulated conductors so that a current from the head 23 of the.elec-- I trode 22 by jumping across the gaps from reach thev shell 5 and be toward the grounding s ell 5.

In the plug shown in'the drawings it will be obvious that by pursuing the shortest possible route from'the central electrode 22 to the shell 5 the igniting current will be compelled to jump a number of gaps with a corresponding number of sparks and that at each time a current branches from the most direct route additional sparks will be produced.

Should carbon collect on the posts 28 or the terminal head 23 in sufiicient quantities.

to form a short circuit between any two of them there will remain several gaps that a spark must ump before reaching the ground terminal or shell 5 and the plug therefore cannot be completely short circuited by carbon unless sufiicient carbon is deposited to form acontinuous bridge between the terminal head 23 and the shell.

The foregoing description taken with the accompanying drawings discloses what is ameter than said opening extending lengthwise therethrough, said sleeve having a head of relatively large diameter disposed within the enlarged lower portion of the shell opening, and spaced from the walls thereof, said head having a convex extremity, insulating material surrounding said head, a copper jacket enclosing said insulating material the lower edge of said copper jacket and the lower edge of said shell being bent over the edge of said head, a cap of insulating material arranged to seat on said shell and having an annular projection extending into the annular space between said shell and said a sleeve, an electrode extending lengthwise through said sleeve, the lower end of said electrode protruding a short distance from the center of said head, and a plurality of metal posts embedded in said head in spaced relations between said central electrode and said shell.

Signed at Seattle, Vashington, this 25th day of August 1920.

GABRIEL MAROTTA.

Vitnesses:

PIERRE BARNES, MARGARET G. S PPLE. 

